1. Field of the Invention
This invention relates to a vertical movement clip for use in maintaining a non-load bearing exterior curtain wall to a building framework. In addition, it relates to a retainer system of the vertical movement clip in use with C shaped channeled stud members such as set forth in U.S. Pat. No. 4,235,054.
2. Description of the Prior Art
In present day architecture most large buildings utilize a support structure of a framework comprising vertical steel columns with horizontal steel beams supported therebetween, floors and a roof. The support structure is then covered on the exterior with non-load bearing exterior finish usually made up of panels or walls that are positioned one adjacent the other.
While the support structure, floors or roofs are designed to bear a calculated maximum load they also must be permitted to receive and maintain a live load due to deflection of the floors or roof and support structure. Therefore, if the non-load exterior finish panels were fixed and yielding the panels could be cracked, broken and damaged because of inflexibility.
Thus, means are needed to attach to the support structure, that will receive exterior stud members to which the exterior panels may be attached and yet allow the stud members to react to live loads and preserve the relationship of the non-load bearing exterior finish panels or walls.
Heretofore L shaped plates or clips which are only simple angle iron clips with a leg welded to a building support with the side having an elongated slot to receive a bolt or screw to secure it to a C shaped stud member were used. This bolt or screw means required a fixing of the clip or L shaped plate permanently to an exterior C shaped channeled stud. Such fixing, if the bolts were too tight would not allow for building shifting and particularly the exterior building panels that are secured to the C shaped studs.
In addition, to the above there is also a vertical movement clip covered by U.S. Pat. No. 4,121,391. This clip is again a simple L shaped clip. However, it bears improvements over the aforementioned L shaped plate in that the leg portion was actually stepped with the inner step portion spaced from the lower most surface of the leg a thickness to accommodate the thickness of a leg of a C shaped stud. Further at the inner end of the step a slot is cut through the leg and continues into the side portion normal to the plane of the leg. The slot is provided to receive a flange of a C shaped stud that is bent normal to the leg and extends therefrom.
The disadvantage of the clip in U.S. Pat. No. 4,121,391 is that it possesses little if any strength and tests have been performed to the point that it will not meet the 10% deviation criteria outlined in section 6.2 of the A.I.S.I. specification. Because of the construction the clips have a tendency to easily break from the building structure.